Then there are the moments when something seems to be going wrong, when one or more areas of the business just don't seem to be working. Cash flow is anemic or the marketing message is flat. Perhaps customers have shown a marked interest in only one particular product or service, ignoring all your other offerings. This means it's time to revisit your business plan, more precisely it's time to revisit the questioning process that helped you craft your plan.
I teach that you should seek to learn from competitors; obviously never copy another business's idea or what they are doing, but you can absolutely learn from their mistakes or see what they are doing and discover ways to improve it. All of that analysis belongs in your business plan: make sure you have your competitors under the microscope and make sure that is a solid chunk of your plan. That is some of the best research and information you will gather about what will make your business successful in future.